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Introduction: Pulpal blood flow oscillation in luxated incisors was assessed non-invasively by laser Doppler flowmetry (LDF), and usefulness of both low-frequency and heartbeat synchronous oscillatory components in the flowmetric signal was discussed. Patients and methods: A total of 20 children aged 7-15 years and 8 healthy adults were included in this study. A LDF probe was positioned at the buccal surface of each tooth at least 2 mm apart from the gingival margin by using a dark coloured rubber splint, and the pulpal blood flow was continuously measured. Flowmetric signal from the luxated teeth was compared with that from control teeth. This research project was approved by the Research Ethics Committee of Nihon University School of Dentistry. Results: Pulpal vitality of luxated teeth could be assessed more precisely by introducing power spectral analysis (maximum entropy method) into detection of both low-frequency and heartbeat synchronous fluctuations in the flowmetric signals. Lowfrequency fluctuations (0.01-0.05 Hz) as well as fluctuations synchronous with the heartbeat were observed in the flowmetric signals from luxated upper incisors in which the pulps had survived the trauma. These periodic fluctuations were not detected in the flowmetric signals from non-vital teeth. A luxated tooth that was accompanied by root fracture showed a gradual decrease in blood flow level concomitantly with the formation of secondary dentin in the pulp chamber. Conclusion: Detection of both low-frequency and heartbeat synchronous fluctuations in the flowmetric signal increases the reliability of LDF for the assessment of pulpal vitality in luxated teeth.